Your midwife does not perform ultrasounds, but will refer you to your nearest imaging center or sonographer for an ultrasound, should you desire or need one. Routine ultrasounds are optional.

The American Pregnancy Association explains what an ultrasound or sonogram is, and what information you can get from them on their website. An ultrasound allows the midwife to evaluate the baby at different stages of development. Ultrasound exams are considered noninvasive, and they do not involve any exposure to radiation. While there is some evidence that cells may heat up during prolonged exposure to ultrasound, there are no current studies that determine that ultrasound is unsafe.

An early ultrasound may be recommended if you are not sure of your last menstrual period, or if you have irregular cycles and are not sure when you got pregnant. An ultrasound is not required for this reason, as there are many physical markers that may be used to determine dates.

A routine anatomical scan is usually recommended around 20 weeks gestation to evaluate the development of the brain, spine, heart, gut, kidneys, and skeleton of the fetus. You may also try to find out the sex of the baby at this point in pregnancy.

Another ultrasound may be ordered to follow up on any genetic screening with positive results. The follow-up includes a Level II ultrasound to look for any physical markers of genetic abnormalities.

A Biophysical Profile (BPP) may be necessary at the end of pregnancy to determine fetal well-being. This is usually performed between 41 and 42 weeks of pregnancy. The Biophysical Profile is an ultrasound examination of the fetus to grade fetal movement, fetal tone, fetal breathing movements, amniotic fluid volume, and the efficiency of the placenta. This ultrasound is usually coupled with a Non-Stress Test (NST) which measures the fetal heart rate and variability in the heart rate to determine fetal well-being.